Below are a few tips for pruning groundcover plants.
When properly spaced, most groundcover plants require very little if any pruning. Part of the reason for planting a groundcover is to allow them to grow and cover space in the landscape. However, sometimes a groundcover grows outside its boundaries and will require some pruning around the edges to keep the plant in bounds.
When a groundcover plant grows out of bounds simply cut the foliage back. Try to prune growth from underneath taller groundcovers, allowing fresh growth and foliage on the top to fall down at edge.
When selecting groundcovers to plant, do a little preliminary research to find plants that are most suitable for the area in the garden you intend on planting them. Particularly look for the mature width of the plant. If the mature width is 6 feet, plant the plant at least 3 feet inside the bed, rather than right on the edge. Doing so might mean you won't have to prune later to keep the plant in bounds.
Some groundcover plants, such as Liriope (Monkey Grass) can be mowed during late winter to remove all of the previous years foliage that may look dingy. Make sure you mow BEFORE new growth begins to emerge in spring.
When Ivy (Hedera helix) and other climbing plants that attch themselves to porous surfaces are growing in your landscape do not allow them to grow up tree trunks past 3 or 4 feet, and do not allow them to grow out of control in woodland areas.